Hybrid vehicle control device

ABSTRACT

A hybrid vehicle control device for a drive system is provided with an engine, a motor and an automatic transmission. The hybrid vehicle control device is configured such that when there is a mode switch request during an EV mode where only the motor is used as a drive source, a shift is made to an HEV mode where the engine and the motor are used as drive sources. The hybrid vehicle control device is further configured such that if a mode switch request and a downshift request for the automatic transmission (are generated, mode switch control is immediately started first. The configuration is also such that downshift control is started once the rotational speed of the engine has reached a combustion possible rotational speed, and the transmission speed at this time is made to be faster than an ordinary transmission speed.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a U.S. National stage application of InternationalApplication No. PCT/JP2013/077184, filed Oct. 4, 2013.

BACKGROUND

Field of the Invention

The present invention relates to a hybrid vehicle control device upon ageneration of a mode switch request from an electric vehicle travelingmode to a hybrid vehicle traveling mode, and a downshift request of theautomatic transmission.

Background Information

Conventionally, a hybrid vehicle control device is known in which, if atransmission request and a mode switch request from an electric vehicletraveling mode to a hybrid vehicle traveling mode are generated, a modeswitch control is started first, then a transmission control of theautomatic transmission is started after fuel injection and ignition ofthe engine is ended and engine start is completed (for example refer toJapanese Laid Open Patent Application No. 2009-234292).

SUMMARY

However, in the conventional hybrid vehicle control device, transmissioncontrol is started after waiting for the completion of engine start, butthe transmission speed at this time is not at all considered.Consequently, there is a problem that the timing of transmissioncompletion is delayed compared to when starting transmission control atthe same time as a transmission request. In view of the problemdescribed above, an object of the present invention is to provide ahybrid vehicle control device that is able to prevent a delay intransmission response when a mode switch request and a downshift requestare generated.

In order to achieve the object described above, the present invention isequipped with a cooperative control means, in a hybrid vehicle controldevice in which an engine, a first clutch, a motor, and an automatictransmission are provided to a drive system, and in which when there isa mode switch request during an electric vehicle traveling mode wherethe first clutch is released and only the motor is a drive source, theengine is started and the first clutch is engaged, and a shift is madeto a hybrid vehicle traveling mode where the engine and the motor aredrive sources. If the mode switch request and a downshift request forthe automatic transmission are generated, the cooperative control meansimmediately starts a mode switch control. Then, downshift control isstarted once the rotational speed of the engine has reached a combustionpossible rotational speed. Furthermore, this cooperative control meanscomprises a transmission speed control section which sets thetransmission speed to be faster during a downshift control when the modeswitch request and the downshift request for the automatic transmissionare generated, than the transmission speed during a downshift controlwhen only the downshift request of the automatic transmission isgenerated.

Therefore, in the hybrid vehicle control device of the presentinvention, in a downshift control that is started once the rotationspeed of the engine has reached a combustion possible rotational speed,the transmission speed at this time is made to be faster than thetransmission speed during a downshift control when only a downshiftrequest is generated. That is, the downshift control when only adownshift request is generated is started immediately after thegeneration of the downshift request. In contrast, a downshift controlwhen both a mode switch request and a downshift request are generatedwaits until the rotation speed of the engine has reached a combustionpossible rotational speed before starting. Consequently, while the timefrom the generation of the request to starting of the control isrelatively short in a downshift control when only a downshift request isgenerated, the time from the generation of the request to starting ofthe control becomes relatively long in a downshift control when both amode switch request and a downshift request are generated. Here, whenboth a mode switch request and a downshift request are generated, thetransmission speed control section makes the transmission speed at thistime to be faster than when only a downshift request is generated;therefore, the time from start to completion of the downshift controlcan be shortened. As a result, a delay in transmission response can beprevented when a mode switch request and a downshift request have beengenerated.

BRIEF DESCRIPTION OF THE DRAWINGS

Referring now to the attached drawings which form a part of thisoriginal disclosure.

FIG. 1 is an overall system view illustrating an FF hybrid vehicle towhich is applied the control device of the first embodiment.

FIG. 2 is a flowchart illustrating the flow of a modeswitch/transmission cooperative control steps (cooperative controlmeans) that are executed by a hybrid control module.

FIG. 3 is a view illustrating one example of a mode selection map.

FIG. 4 is a view illustrating one example of a shifting diagram of abelt type continuously variable transmission.

FIG. 5 is a block view illustrating a transmission speed calculationsteps that are executed by the hybrid control module of the firstembodiment.

FIG. 6 is a time chart illustrating each characteristic of a mode switchrequest, engine rotation speed determination, transmission ratio, enginerotation speed, transmission input rotational speed, and motor rotationspeed, when a mode switch request and a downshift request are present,in the control device of the first embodiment.

FIG. 7 is a block view illustrating another example of the transmissionspeed calculation steps that are executed by the hybrid control module.

DETAILED DESCRIPTION OF THE EMBODIMENTS

A preferred embodiment for realizing the hybrid vehicle control deviceof the present invention is described below based on the firstembodiment illustrated in the drawings.

First Embodiment

First, the “overall system configuration of an FF hybrid vehicle,” the“detailed configuration of the mode switch/transmission cooperativecontrol,” and the “detailed configuration of the transmission speedcalculation steps” will be separately described regarding theconfiguration of the hybrid vehicle control device of the firstembodiment.

Overall System Configuration of an FF Hybrid Vehicle

FIG. 1 is an overall system view illustrating an FF hybrid vehicle towhich is applied the control device of the first embodiment. The overallsystem configuration of an FF hybrid vehicle to which is applied thehybrid vehicle control device of the first embodiment will be describedbelow, based on FIG. 1.

A drive system of an FF hybrid vehicle (one example of a hybrid vehicle)is provided with a starter motor 1, a transverse engine 2, a firstclutch 3 (abbreviated “CL1”), a motor/generator (motor) 4, a secondclutch 5 (abbreviated “CL2”), and a belt type continuously variabletransmission 6 (abbreviated “CVT”: automatic transmission), asillustrated in FIG. 1. An output shaft of the belt type continuouslyvariable transmission 6 is drivingly coupled to left and right frontwheels 10L, 10R, via a final reduction gear train 7, a differential gear8, and left and right drive shafts 9L, 9R. The left and right rearwheels 11L, 11R are configured as driven wheels.

The starter motor 1 is a cranking motor having a gear that meshes withan engine starting gear provided to a crankshaft of the transverseengine 2, and which rotationally drives the crankshaft at the time ofengine start.

The transverse engine 2 is an engine disposed in a front room with thecrankshaft direction as the vehicle width direction, comprising anelectric water pump 12, and a crankshaft rotation sensor 13 that detectsa reverse rotation of the transverse engine 2.

The first clutch 3 is a hydraulically actuated normally open drymulti-plate friction clutch which is interposed between the transverseengine 2 and the motor/generator 4, in which complete engagement/slipengagement/disengagement are controlled by a first clutch hydraulicpressure.

The motor/generator 4 is a three-phase alternating current permanentmagnet type synchronous motor which is coupled to the transverse engine2 via the first clutch 3. This motor/generator 4 uses a high powerbattery 21 described below as the power source, and an inverter 26,which converts direct current to three-phase alternating current duringpowering and converts three-phase alternating current to direct currentduring regeneration, is connected to the stator coil via an AC harness27.

The second clutch 5 is a hydraulically actuated normally open drymulti-plate friction clutch which is interposed between themotor/generator 4 and the left and right front wheels 10L, 10R, whichare drive wheels, in which complete engagement/slipengagement/disengagement are controlled by a second clutch hydraulicpressure. The second clutch 5 of the first embodiment is configured bydiverting a forward clutch 5 a and a reverse brake 5 b provided to aforward/reverse switching mechanism of the belt type continuouslyvariable transmission 6 configured by a planetary gear. That is, theforward clutch 5 a is used as the second clutch 5 during forwardtraveling, and the reverse brake 5 b is used as the second clutch 5during reverse traveling.

The belt type continuously variable transmission 6 is a transmissionthat achieves a stepless transmission ratio by changing the windingdiameter of the belt by applying shifting hydraulic pressure to aprimary oil chamber and a secondary oil chamber. This belt typecontinuously variable transmission 6 comprises a main oil pump 14(mechanical drive), a sub oil pump 15 (motor drive), and anunillustrated control valve unit that produces the first and secondclutch hydraulic pressure and the shifting hydraulic pressure, using theline pressure PL generated by adjusting the pump discharge pressure fromthe main oil pump 14 as the source pressure. The main oil pump 14 isrotationally driven by a motor shaft of the motor/generator 4(transmission input shaft). The sub oil pump 15 is mainly used as anauxiliary pump for producing lubrication and cooling oil.

A one-motor-two-clutch drive system is configured by the first clutch 3,the motor/generator 4, and the second clutch 5, and this drive systemcomprises an “EV mode” and an “HEV mode” as the main traveling modes(drive modes) thereof. The “EV mode” is an electric vehicle travelingmode in which the first clutch 3 is released and the second clutch 5 isengaged, and in which the motor/generator 4 is the only drive source;traveling by this “EV mode” is referred to as “EV traveling”. The “HEV”mode is a hybrid vehicle traveling mode in which the first and secondclutches 3, 5 are engaged, and in which the transverse engine 2 and themotor/generator 4 are the drive sources; traveling by this “HEV mode” isreferred to as “HEV traveling.”

The regenerative cooperation brake unit 16 in FIG. 1 is a device thatcontrols the total braking torque, accompanying the fact thatregenerative operation is carried out in principle during brakeoperation. This regenerative cooperation brake unit 16 comprises a brakepedal, a negative pressure booster that uses the intake negativepressure of the transverse engine 2, and a master cylinder. Then, at thetime of a brake operation, the unit carries out a cooperative control ofthe regeneration amount/fluid pressure amount, so that the amountobtained by subtracting the regenerative braking force from therequested braking force based on the pedal operation amount is allottedto the hydraulic braking force.

The power supply system of the FF hybrid vehicle is provided with a highpower battery 21 as the motor/generator power source, and a 12V battery22 as a 12V system load power source, as illustrated in FIG. 1.

The high power battery 21 is a secondary battery mounted as the powersource of the motor/generator 4, and, for example, a lithium ion batteryis used therefor, in which a cell module configured from a number ofcells is set inside a battery pack case. A junction box which aggregatesa relay circuit for carrying out supply/cutoff/distribution of heavycurrent is built in to this high power battery 21, and further attachedthereto are a cooling fan unit 24 having a battery cooling function, anda lithium battery controller 86 which monitors the battery chargecapacity (battery SOC) and the battery temperature.

The high power battery 21 and the motor/generator 4 are connected to theDC harness 25 and the inverter 26 via the AC harness 27. A motorcontroller 83 for performing powering/regeneration control is attachedto the inverter 26. That is, the inverter 26 converts the direct currentfrom the DC harness 25 to a three-phase alternating current to the ACharness 27 during powering, when the motor/generator 4 is driven by thedischarge of the high power battery 21. In addition, the inverterconverts the three-phase alternating current from the AC harness 27 to adirect current to the DC harness 25, during regeneration for chargingthe high power battery 21 with the power generation by themotor/generator 4.

The 12V battery 22 is a secondary battery mounted as a power source of a12V system load, which is an auxiliary machine; for example, a leadbattery mounted on an engine vehicle or the like is used. The high powerbattery 21 and the 12V battery 22 are connected via a DC branch harness25 a, a DC/DC converter 37, and a battery harness 38. The DC/DCconverter 37 is for converting several hundred volts from the high powerbattery 21 to 12V, which is configured to manage the charging amount ofthe 12V battery 22 by controlling this DC/DC converter 37 with thehybrid control module 81.

The control system of an FF hybrid vehicle comprises a hybrid controlmodule 81 (abbreviated: “HCM”) as an integrated control means having afunction to appropriately manage the energy consumption of the entirevehicle, as illustrated in FIG. 1. An engine control module 82(abbreviated: “ECM”), a motor controller 83 (abbreviated: “MC”), a CVTcontrol unit 84 (abbreviated “CVTCU”), and a lithium battery controller86 (abbreviated: “LBC”) are provided as control means that are connectedto this hybrid control module 81. These control means including thehybrid control module 81 are connected so as to be capable of exchangingbidirectional information by a CAN communication line 90 (CAN is anabbreviation for “Controller Area Network”).

The hybrid control module 81 carries out various controls, based oninput information from each of the control means, an ignition switch 91,an accelerator position opening amount sensor (accelerator positionopening amount detection means) 92, a vehicle speed sensor (vehiclespeed detection means) 93, and the like. The engine control module 82carries out fuel injection control, ignition control, fuel cut control,and the like of the transverse engine 2. The motor controller 83 carriesout powering control, regenerative control, and the like of themotor/generator 4 by the inverter 26. The CVT control unit 84 carriesout the engagement hydraulic pressure control of the first clutch 3, theengagement hydraulic pressure control of the second clutch 5, theshifting hydraulic pressure control of the belt type continuouslyvariable transmission 6, and the like. The lithium battery controller 86manages the battery SOC, the battery temperature, and the like of thehigh power battery 21.

Furthermore, here, a timer (stop time detection means) 82 a is builtinto the engine control module 82, which counts the stopped time of thetransverse engine 2 while the ignition switch 91 is being controlled ON.

Detailed Configuration of the Mode Switch/Transmission CooperativeControl

FIG. 2 is a flowchart illustrating the flow of a modeswitch/transmission cooperative control steps (cooperative controlmeans) that are executed by the hybrid control module. Each step in FIG.2 showing the detailed configuration of the mode switch/transmissioncooperative control steps will be described below. The control steps areexecuted when the traveling mode is switched to the “EV mode.”

In Step S1, the stopped time of the transverse engine 2 (hereinafterreferred to as “engine stop time”) is counted, and the steps proceed toStep S2. Here, the “engine stop time” is the time that the transverseengine 2 is stopped due to the traveling mode being switched to the “EVmode.” This is the time that the transverse engine 2 is stopped before amode switch control from the “EV mode” to the “HEV mode” is started. Thecounting of this “engine stop time” is carried out by a timer 82 aprovided to the engine control module 82.

In Step S2, following the counting of the engine stop time in Step S1,it is determined whether or not a mode switch request of the travelingmode in the FF hybrid vehicle from the “EV mode” to the “HEV mode”(hereinafter referred to as “EV

HEV switch request”) has been generated. If YES (switch requestpresent), the steps proceed to Step S3. If NO (switch request notpresent), the steps proceed to Step S13. Here, the “EV

HEV switch request” is outputted when the operating point (APO, VSP),which is determined by the accelerator position opening amount and thevehicle speed, moves from the “EV region” to the “HEV region” aftercrossing the EV

HEV switching line (engine start line), in the mode selection mapillustrated in FIG. 3.

In Step S3, following the determination that an “EV

HEV switch request” is present in Step S2, it is determined whether ornot a downshift request of the belt type continuously variabletransmission 6 has been outputted. If YES (downshift request present),the steps proceed to Step S4. If NO (downshift request not present), thesteps proceed to Step S15. Here, the “downshift request” is outputtedwhen the operating point (N_(CVT), VSP), which is determined by thetransmission input rotational speed and the vehicle speed, moves fromthe current position toward the lowest transmission line, in theshifting diagram illustrated in FIG. 4.

In Step S4, following the determination that a downshift request ispresent in Step S3, an EV

HEV switch request and a downshift request of the belt type continuouslyvariable transmission 6 are considered to have been generatedsimultaneously; a mode switch control is immediately started/executed,and the steps proceed to Step S5. Here, a “mode switch control” isstarting the transverse engine 2 while engaging the first clutch 3, andtransitioning the drive mode from the “EV mode” to the “HEV mode.” This“mode switch control” comprises an engine start step that engages thefirst clutch 3, raises the engine rotation speed by rotating thecrankshaft of the transverse engine 2 with the motor/generator 4, andcarries out fuel injection and ignition after the engine rotation speedhas reached a combustion possible rotational speed, and a first clutchengagement step that engages the first clutch 3 and transmits thedriving force of the transverse engine 2 to the left and right frontwheels 10L, 10R, which are driving wheels. This engine start steps andfirst clutch engagement steps are executed in parallel. The engine startsteps may be executed using the starter motor 1 as well.

In Step S5, following the start/execution of the mode switch control inStep S4, it is determined whether or not the rotation speed of thetransverse engine 2 has reached a combustion possible rotational speed.If YES (engine rotation speed≧combustion possible rotational speed), thesteps proceed to Step S6. If NO (engine rotation speed≦combustionpossible rotational speed), the steps return to Step S4. Here, a“combustion possible rotational speed” is a rotation speed with whichthe transverse engine 2 becomes capable of autonomous rotation, and arotation speed with which engine rotation can be maintained by fuelinjection and ignition.

In Step S6, following the determination that engine rotationspeed≧combustion possible rotational speed in Step S5, a downshiftcontrol in the belt type continuously variable transmission 6 isstarted, and the steps proceed to Step S7. At this time, the mode switchcontrol is continued to be executed. Here, a “downshift control” is acontrol in which the transmission ratio in the belt type continuouslyvariable transmission 6 is changed to the low side. This “downshiftcontrol” comprises a hydraulic pressure control step for changing thewinding diameter of the belt by applying shifting hydraulic pressure toa primary oil chamber and a secondary oil chamber of the belt typecontinuously variable transmission 6, and a motor rotation speed controlstep for raising the rotation speed of the motor/generator 4, which isthe transmission input rotational speed. The hydraulic pressure controlsteps and motor rotation speed control steps are executed in parallel.

In Step S7, following the start of the downshift control in Step S6, aCL1 pre-engagement transmission speed is calculated, and the stepsproceed to Step S8. Here, the “CL1 pre-engagement transmission speed” isthe transmission speed during a downshift control that is executedbefore the first clutch 3 is completely engaged. The calculation of thistransmission speed will be described below.

In Step S8, following the calculation of the CL1 pre-engagementtransmission speed in Step S7, a downshift control is executed at theCL1 pre-engagement transmission speed calculated in Step S7, and thesteps proceed to Step S9.

In Step S9, following the execution of the downshift control in Step S8,it is determined whether or not the engagement of the first clutch 3 hasbeen completed, that is, whether or not the first clutch 3 is fullyengaged. If YES (CL1 engaged), the steps proceed to Step S10. If NO (CL1non-engaged), the steps return to Step S7. Here, the complete engagementof the first clutch 3 is determined when the rotation speed of thetransverse engine 2 and the rotation speed of the motor 4 match.

In Step S10, following the determination that CL1 is engaged in Step S9,a CL1 post-engagement transmission speed is calculated, and the stepsproceed to Step S11. Here, the “CL1 post-engagement transmission speed”is the transmission speed during a downshift control that is executedafter the first clutch 3 is completely engaged.

In Step S11, following the calculation of the CL1 post-engagementtransmission speed in Step S10, a downshift control is executed at theCL1 post-engagement transmission speed calculated in Step S10, and thesteps proceed to Step S12.

In Step S12, following the execution of the downshift control in StepS11, it is determined whether or not the downshift control has beencompleted. If YES (shifting completed), the steps proceed to END. If NO(shifting not completed), the steps return to Step S10.

In Step S13, following the determination that an “EV

HEV switch request” is not present in Step S2, it is determined whetheror not a downshift request of the belt type continuously variabletransmission 6 has been outputted. If YES (downshift request present),the steps proceed to Step S14. If NO (downshift request not present),the steps return to Step S1, concluding that there is no control thatrequires execution.

In Step S14, following the determination that a downshift request ispresent in Step S13, an ordinary transmission control isstarted/executed, and the steps return to Step S1. Here, an “ordinarytransmission control” is immediately carrying out a downshift control atan ordinary transmission speed which is set in advance when a downshiftrequest is outputted.

In Step S15, following the determination that a downshift request is notpresent in Step S3, an ordinary mode switch control is started/executed,and the steps proceed to END.

Here, an “ordinary mode switch control” is immediately carrying out amode switch control when a mode switch request is outputted.

Detailed Configuration of the Transmission Speed Calculation Steps

FIG. 5 is a block view illustrating the transmission speed calculationsteps that are executed by the hybrid control module of the firstembodiment. The detailed configuration of the transmission speedcalculation steps of the first embodiment will be described below, basedon FIG. 5.

The transmission speed during the downshift control in the firstembodiment is set by the transmission speed calculation stepsillustrated in FIG. 5. That is, this transmission speed calculationsteps comprise a transmission speed calculation block during cooperativecontrol A, a transmission speed setting block during ordinary control B,and a third switch SW3.

The transmission speed calculation block during cooperative control Acalculates the transmission speed that is applied when a mode switchrequest and a downshift request are generated (hereinafter referred toas “transmission speed during cooperative control”). This transmissionspeed calculation block during cooperative control A comprises a mapA/map B/map C which are set in advance, a first switch SW1 and a secondswitch SW2.

The map A, map B, and map C are all transmission speed setting mapswhich uniquely set the transmission speed, on the basis of theaccelerator position opening amount detected by the accelerator positionopening amount sensor 92, the accelerator depression speed at this time,and the vehicle speed detected by the vehicle speed sensor 93. Theaccelerator position opening amount and the accelerator depression speedare parameters that indicate the required driving force of the driver.

The map A sets a transmission speed that is applied before the firstclutch 3 is completely engaged, and when the engine stop time which iscounted by the timer 82 a is longer than a predetermined time. Thetransmission speed setting conditions in this map A are as listed below.

(1) When the accelerator position opening amount is at a medium openingamount or more.

Set to a value faster than the ordinary transmission speed.

Set to a faster value as the accelerator position opening amount and theaccelerator depression speed are increased, that is, as the requireddriving force of the driver is increased.

Set to a slower value as the vehicle speed is increased.

Set an upper limit value so as not to delay the engagement of the firstclutch 3.

(2) When the accelerator position opening amount is a low opening amountand the depression speed is low.

Set to a value slower than the ordinary transmission speed.

Here, the “predetermined time” which is the reference for determiningthat the “engine stop time is long” is a time with which it is possibleto secure an engine suction pressure that can obtain an engine torquethat allows a quick engine rotation rise at the time of engine start.When the engine stop time is short, the air inside the transverse engine2 is expanded due to heating, the engine intake pressure becomes low,and an engine torque cannot be outputted. As a result, the enginerotation rise is slowed, the engagement of the first clutch 3 takestime, and the mode switch time becomes long. That is, in this map A, thetime with which it can be determined that the engine rotation rise willnot be slowed due to not being able to obtain the engine intakepressure, and the transmission speed that is to be applied when thetransverse engine 2 is stopped are set.

In addition, “accelerator position opening amount is at a medium openingamount” is an accelerator depression state of a level at which it can bedetermined that a required driving force of the driver is clearly beinggenerated. Additionally, “accelerator position opening amount is at alow opening amount” is an accelerator depression state of a level atwhich it can be determined that a required driving force of the driveris hardly generated, or is not generated at all. Furthermore,“depression speed is low” is an accelerator depression speed of a levelat which it can be determined that a required driving force of thedriver is hardly generated, or is not generated at all.

Furthermore, an “upper limit value so as not to delay the engagement ofthe first clutch 3” is a value for preventing the engagement of thefirst clutch 3 being delayed due to the increase rate of the enginerotation speed not being able to catch up, if the increase rate of themotor rotation speed is made too fast, when increasing the motorrotation speed in order to increase the transmission input rotationalspeed accompanying a downshift control. That is, by suppressing thetransmission speed, an excessively fast increase in the motor rotationspeed can be suppressed, and the engine rotation speed and the motorrotation speed can be matched at an appropriate timing.

The map B sets a transmission speed that is applied before the firstclutch 3 is completely engaged, and when the engine stop time which iscounted by the timer 82 a is equal to or less than a predetermined time.The transmission speed setting conditions in this map B are as listedbelow.

(1) When the accelerator position opening amount is at a medium openingamount or more.

Set to a value faster than the ordinary transmission speed, but a valuethat is slower than the setting value in map A.

Set to a faster value as the accelerator position opening amount and theaccelerator depression speed are increased, that is, as the requireddriving force of the driver is increased.

Set to a slower value as the vehicle speed is increased.

Set an upper limit value so as not to delay the engagement of the firstclutch 3.

(2) When the accelerator position opening amount is a low opening amountand the depression speed is low.

Set to a value slower than the ordinary transmission speed, and a valuethat is slower than in map A.

The map C sets a transmission speed that is applied after the firstclutch 3 is completely engaged. The transmission speed settingconditions in this map C are as listed below.

(1) When the accelerator position opening amount is at a medium openingamount or more.

Set to a value faster than the ordinary transmission speed.

Set to a faster value as the accelerator position opening amount and theaccelerator depression speed are increased, that is, as the requireddriving force of the driver is increased.

Set to a slower value as the vehicle speed is increased.

An upper limit value is not set, since the first clutch 3 is engaged.

(2) When the accelerator position opening amount is a low opening amountand the depression speed is low.

Set to a value slower than the ordinary transmission speed.

The first switch SW1 and the second switch SW2 are both selectionoperators for selecting the transmission speed that meets apredetermined condition from a plurality of inputted transmissionspeeds.

The first switch SW1 selects one transmission speed from a “transmissionspeed when stopped time is long” that is applied when the engine stoptime set based on map A is long, and a “transmission speed when stoppedtime is short” that is applied when the engine stop time set based onmap B is short, based on the actual engine stop time that is counted bythe timer 82 a, and sets a “CL1 pre-engagement transmission speed” thatis applied before the first clutch 3 is completely engaged.

Specifically, if the actual engine stop time is longer than apredetermined time, the “transmission speed when stopped time is long”is selected as the CL1 pre-engagement transmission speed. Additionally,if the actual engine stop time is shorter than a predetermined time, the“transmission speed when stopped time is short” is selected as the CL1pre-engagement transmission speed.

The second switch SW2 selects one transmission speed from a “CL1pre-engagement transmission speed” that is selected and set by the firstswitch SW1, and a “CL1 post-engagement transmission speed” that is seton the basis of map C, based on the results of the engagementdetermination of the first clutch 3, and sets a “transmission speedduring cooperative control” that is applied when a mode switch requestand a downshift request are generated.

Specifically, if the CL1 engagement determination is YES (first clutch 3is in a completely engaged state), the “CL1 post-engagement transmissionspeed” is selected as the transmission speed during cooperative control.In addition, if the CL1 engagement determination is NO (first clutch 3is in a state of not being completely engaged), the “CL1 pre-engagementtransmission speed” is selected as the transmission speed duringcooperative control.

An ordinary transmission speed that is set in advance is stored in thetransmission speed setting block during ordinary control B.

The third switch SW3 is a selection operator for selecting thetransmission speed that meets a predetermined condition from a pluralityof inputted transmission speeds. That is, in this third switch SW3, onetransmission speed is selected from a transmission speed duringcooperative control that is set in the transmission speed calculationblock during cooperative control A, and an ordinary transmission speedthat is stored in the transmission speed setting block during ordinarycontrol B, based on the results of the mode switch requestdetermination, to set the “transmission speed” at the time of downshiftcontrol.

Specifically, if the mode switch request determination is YES (state inwhich “EV

HEV switch request” has been outputted), the “transmission speed duringcooperative control” is selected as the transmission speed. In addition,if the mode switch request determination is NO (state in which “EV

HEV switch request” has not been outputted), the “ordinary transmissionspeed” is selected as the transmission speed.

Next, the “transmission speed changing action,” the “first clutchengagement action,” and the “torque fluctuation suppression action” willbe separately described regarding the actions of the FF hybrid vehiclecontrol device of the first embodiment.

Transmission Speed Changing Action

FIG. 6 is a time chart illustrating each characteristic of a mode switchrequest, engine rotation speed determination, transmission ratio, enginerotation speed, transmission input rotational speed, and motor rotationspeed, when a mode switch request and a downshift request are present,in the control device of the first embodiment. The transmission speedchanging action of the first embodiment will be described below, basedon FIG. 6.

When the FF hybrid vehicle of the first embodiment is traveling in the“EV mode,” the flowchart illustrated in FIG. 2 (mode switch/transmissioncooperative control steps) are executed, the steps proceed from Step S1to Step S2, and the stopped time of the transverse engine 2 is countedwhile it is determined whether or not an “EV

HEV switch request” has been outputted.

Here, if an “EV

HEV switch request” is not being outputted, the steps proceed to StepS13, and it is determined whether or not a downshift request has beenoutputted. If a downshift request is outputted, the steps proceed toStep S14. At this time, since only a downshift request is beingoutputted, a downshift control is immediately started/executed.Regarding the transmission speed at this time, an “EV

HEV switch request” has not been outputted, and the mode switch requestdetermination is NO. Accordingly, the “ordinary transmission speed” isselected as the transmission speed by the third switch SW3 in thecalculation steps illustrated in FIG. 5. As a result, the transmissionspeed will be the ordinary transmission speed which is set in advance.Then, the steps proceed to Step S1 to continue the counting of theengine stop time. In addition, if a downshift request has not beenoutputted following the “EV

HEV switch request,” the steps return to Step S1 since there is nocontrol to execute, and the counting of the engine stop time iscontinued.

On the other hand, when an “EV

HEV switch request” is outputted, the steps proceed to Step S3, and itis determined whether or not a downshift request has been outputted. Ifa downshift request has not been outputted, the steps proceed to StepS15. At this time, since only an “EV

HEV switch request” is being outputted, a mode switch control isimmediately started/executed. The traveling mode is thereby switchedfrom the “EV mode” to the “HEV mode,” and the mode switch/transmissioncooperative control steps illustrated in FIG. 2 are ended.

In addition, if it is determined that an output of a downshift requestis present following the output of the “EV

HEV switch request,” the steps proceed to Step S4 in the flowchart ofFIG. 2, and the mode switch control is immediately started/executed.Accordingly, the rotation speed of the motor/generator 4 is controlledwhile the engagement control of the first clutch 3 is started, and therotation speed of the transverse engine 2 starts to increase due to themotor rotation speed being transmitted to the transverse engine 2 viathe first clutch 3. That is, in the time chart illustrated in FIG. 6,when an “EV

HEV switch request” and a downshift request are outputted at time t₁,the motor rotation speed is first increased to a rotation speed that isrequired for engine cranking by starting/executing a mode switchcontrol. Additionally, the engagement control of the first clutch 3 isstarted. At this time, the second clutch 5 is slip engaged whilesecuring the transmission of the required driving force of the driver.Accordingly, the transmission input rotational speed will not fluctuate.

Then, the steps proceed to Step S5, and it is determined whether or notthe engine rotation speed has reached the combustion possible rotationalspeed and is capable of autonomous rotation. That is, when the enginerotation speed reaches the combustion possible rotational speed at timet₂, the engine rotation speed determination is switched to ON.Accordingly, the steps proceed to Step S5→Step S6→Step S7→Step S8, adownshift control of the belt type continuously variable transmission 6is started, the CL1 pre-engagement transmission speed is firstcalculated, and the downshift control is executed according to this CL1pre-engagement transmission speed.

Here, the CL1 pre-engagement transmission speed is calculated based onthe accelerator position opening amount/accelerator depressionspeed/vehicle speed and on the map A or map B in the calculation stepsillustrated in FIG. 5. At this time, if the engine stop time before timet₁ is longer than a predetermined value and the accelerator positionopening amount is a medium opening amount or more, the CL1pre-engagement transmission speed is set to a value that is faster thanthe ordinary transmission speed, based on map A. That is, thetransmission ratio starts to increase from time t₂ with the execution ofthe downshift control, and the slope of the change of the transmissionratio at this time becomes greater than the slope during a downshiftcontrol at the ordinary transmission speed indicated by the dashed line,as illustrated in FIG. 6. This CL1 pre-engagement transmission speed isset to a faster value as the accelerator position opening amount and theaccelerator depression speed are increased, that is, as the requireddriving force of the driver is increased.

Then, at time t₃, when the engine rotation speed and the motor rotationspeed match and the first clutch 3 is engaged, the steps proceed to StepS9→Step S10→Step S11, the CL1 post-engagement transmission speed iscalculated, and the downshift control is executed according to this CL1post-engagement transmission speed.

Here, the CL1 post-engagement transmission speed is calculated based onthe accelerator position opening amount/accelerator depressionspeed/vehicle speed and on the map C in the calculation stepsillustrated in FIG. 5, and is set to a value that is faster than theordinary transmission speed. That is, the slope of the change of thetransmission ratio after time t₃ becomes greater than the slope during adownshift control at the ordinary transmission speed indicated by thedashed line, as illustrated in FIG. 6. In addition, this CL1post-engagement transmission speed is set to a faster value as theaccelerator position opening amount and the accelerator depression speedare increased, that is, as the required driving force of the driver isincreased. Furthermore, in this CL1 post-engagement transmission speed,an upper limit value so as not to delay the engagement of the firstclutch 3 is not set.

Then, the transmission ratio reaches the target transmission ratio whilethe engine rotation speed and the motor rotation speed become stable attime t₄, and the transmission input rotational speed, the enginerotation speed, and the motor rotation speed are matched by the secondclutch 5 being completely engaged at time t₅, at which point thedownshift control is completed. Accordingly, YES is determined in StepS12, and the mode switch/transmission cooperative control is ended.

In contrast, as illustrated by the dashed line in FIG. 6, if a downshiftcontrol is carried out at the ordinary transmission speed from time t₂at which the engine rotation speed reaches the combustion possiblerotational speed, the transmission speed is slower than the firstembodiment; therefore, the transmission ratio reaches the targettransmission ratio at the timing of time t₆, which is later than timet₅.

In this manner, in the hybrid vehicle control device of the firstembodiment, if a mode switch request and a downshift request aregenerated, mode switch control is started first. Then, downshift controlis started once the rotational speed of the transverse engine 2 hasreached a combustion possible rotational speed. Additionally, thetransmission speed during cooperative control which is the transmissionspeed during the downshift control at this time is set to a value thatis faster than the ordinary transmission speed (transmission speed whenonly the downshift request is generated). Accordingly, the downshiftcontrol progresses more quickly than during an ordinary transmission. Asa result, the timing at which the downshift control is completed can beexpedited compared to when carrying out a downshift control at theordinary transmission speed, and a delay in transmission response can beprevented.

In addition, this transmission speed during cooperative control is setto a faster value as the accelerator position opening amount and theaccelerator depression speed are increased, that is, as the requireddriving force of the driver is increased. Accordingly, the transmissionspeed is increased as the required driving force of the driver isincreased, and an improvement in the transmission response can beachieved. The necessary driving force can thereby be quickly obtained.

Then, in the hybrid vehicle control device of the first embodiment, thetransmission speed during cooperative control is divided into the CL1pre-engagement transmission speed that is applied before the firstclutch 3 is completely engaged, and the CL1 post-engagement transmissionspeed that is applied after the first fluid 3 is engaged. Here, in theCL1 post-engagement transmission speed, an upper limit value so as notto delay the engagement of the first clutch 3 is not set. Accordingly,the transmission speed after the first clutch 3 is engaged can be madefaster than the transmission speed before the first clutch 3 is engaged.Accordingly, in a situation in which it is not necessary to consider adelay in the engagement of the first clutch 3, the transmission speedduring a downshift control can be made even faster, and a furtherimprovement in the transmission response can be achieved.

First Clutch Engagement Action

In the hybrid vehicle control device of the first embodiment, thetransmission speed during cooperative control is calculated based on oneof the accelerator position opening amount/accelerator depressionspeed/vehicle speed, and the map A, map B, map C in the calculationsteps illustrated in FIG. 5

At this time, the CL1 pre-engagement transmission speed, which isapplied before the first clutch 3 is engaged, is set to a slower valuewhen the stopped time of the transverse engine 2 is short, compared towhen the engine stop time is long. That is, the CL1 pre-engagementtransmission speed is calculated based on map A or map B but thetransmission speed that is applied when the engine stop time is equal toor less than a predetermined time is set based on map B. In this map B,the transmission speed is set to a value faster than the ordinarytransmission speed, but a value that is slower than the setting value inmap A, when the accelerator position opening amount is at a mediumopening amount or more.

Accordingly, when the engine stop time is short, the engine intakepressure is low, and the rotation rise of the transverse engine 2becomes slow due to lack of engine torque, the transmission speed duringcooperative control becomes relatively slow. Accordingly, when theengagement of the first clutch 3 takes time due to the rotation rise ofthe engine rotation being slow, an increase in the motor rotation speedaccompanying a downshift control can be suppressed by suppressing anincrease in the transmission speed, and it is possible to prevent theengagement of the first clutch 3 taking time, and the engine starttaking more time than necessary.

Additionally, in this CL1 pre-engagement transmission speed, an upperlimit value is set so as not to delay the engagement of the first clutch3. Accordingly, while the motor rotation speed is increased in order toincrease the transmission input rotational speed accompanying adownshift control, it is possible to prevent a delay in the engagementof the first clutch 3, by the increase rate of this motor rotation speedbeing limited, and the engine rotation speed and the motor rotationspeed being matched at an appropriate timing.

Furthermore, in any of the map A, map B, and map C, the transmissionspeed during cooperative control is set to a slower value as the vehiclespeed is increased. Here, the motor rotation speed when executing a modeswitch control or a downshift control is higher when the vehicle speedis fast, compared to when the vehicle speed is slow. At this time, it ispossible to suppress the increase rate of the motor rotation in relationto the increase rate of the engine rotation speed by slowing thetransmission speed during cooperative control, and it is possible toprevent the engagement of the first clutch 3 taking time, and the enginestart taking more time than necessary.

Torque Fluctuation Suppression Action

In the hybrid vehicle control device of the first embodiment, when thetransmission speed during cooperative control is calculated based on oneof the accelerator position opening amount/accelerator depressionspeed/vehicle speed, and the map A, map B, and map C in the calculationsteps illustrated in FIG. 5, the transmission speed during cooperativecontrol is set to a value that is slower than the ordinary transmissioncontrol, if the accelerator position opening amount is a low openingamount and the depression speed is small.

Here, “if the accelerator position opening amount is a low openingamount and the depression speed is small” is a state in which it can bedetermined that a required driving force of the driver is hardlygenerated, or is not generated at all, such as a state in which the footis away from the accelerator. At this time, it can be thought that thedriver does not want a variation in the driving force; therefore, thereis the risk that discomfort is imparted if the driving force is changed.

In contrast, if the accelerator position opening amount is at a lowopening amount and the depression speed is low, the downshift controlwill progress more slowly than during ordinary transmission, by settingthe transmission speed during cooperative control to a value that isslower than the ordinary transmission speed. As a result, an abruptvariation in the driving force is suppressed, and imparting discomfortto the driver can be prevented.

Next, the effects are described. The effects listed below can beobtained with the FF hybrid vehicle control device according to thefirst embodiment.

(1) A hybrid vehicle control device in which an engine (transverseengine) 2, a motor (motor/generator) 4, and an automatic transmission(belt type continuously variable transmission) 6 are provided to a drivesystem, and in which when there is a mode switch request during anelectric vehicle traveling mode (EV mode) where only the motor 4 is adrive source, a shift is made to a hybrid vehicle traveling mode (HEVmode) where the engine 2 and the motor 4 are drive sources, comprising acooperative control means (FIG. 2) which, if the mode switch request anda downshift request of the automatic transmission 6 are generated,immediately starts a mode switch control, and starts a downshift controlonce the rotational speed of the engine 2 has reached a combustionpossible rotational speed, wherein the cooperative control means (FIG.2) is configured to comprise a transmission speed control section (stepS7-step S11) which sets the transmission speed during the downshiftcontrol to be faster than the transmission speed during a downshiftcontrol when only the downshift request of the automatic transmission isgenerated. Accordingly, a delay in transmission response can beprevented when a mode switch request and a downshift request have beengenerated.

(2) The transmission speed control section (Step S7-Step S11) isconfigured to make the transmission speed during the downshift controlto be faster as the required driving force of the driver is increased.Accordingly, in addition to the effect of (1), it is possible to achievean improvement the transmission response as the required driving forceof the driver is increased, and the necessary driving force can bequickly obtained.

(3) Provided with a stop time detection means (timer) 82 a that detectsa stopped time of the engine (transverse engine) 2 before the modeswitch control is started, wherein the transmission speed controlsection (Step S7-Step S11) is configured to make the transmission speedduring the downshift control when the stopped time of the engine 2 isshort to be slower than the transmission speed during the downshiftcontrol when the stopped time of the engine 2 is long. Accordingly, inaddition to the effects of (1) or (2), when the engine stop time isshort, the engine intake pressure is low, and the rotation rise of thetransverse engine 2 becomes slow due to lack of engine torque, anincrease in the motor rotation speed accompanying a downshift controlcan be suppressed, and it is possible to prevent the engine start takingmore time than necessary.

(4) Provided with a vehicle speed detection means (vehicle speed sensor)93 that detects the vehicle speed, wherein the transmission speedcontrol section (Step S7-Step S11) is configured to make thetransmission speed during the downshift control when the vehicle speedis fast to be slower than the transmission speed during the downshiftcontrol when the vehicle speed is slow. Accordingly, in addition to theeffects of any one of (1) to (3), when the vehicle speed is fast and themotor rotation speed is high, it is possible to suppress the increaserate of the motor rotation in relation to the increase rate of theengine rotation speed, and to prevent the engine start taking more timethan necessary.

(5) The drive system is provided with a first clutch 3 interposedbetween the engine 2 and the motor 4, wherein the transmission speedcontrol section (Step S7-Step S11) is configured to make thetransmission speed during the downshift control after the first clutch 3is engaged (CL1 post-engagement transmission speed) to be faster thanthe transmission speed during the downshift control before the firstclutch 3 is completely engaged (CL1 pre-engagement transmission speed).Accordingly, in addition to the effect of any one of (1) to (4), in asituation in which it is not necessary to consider a delay in theengagement of the first clutch 3, the transmission speed during adownshift control can be made even faster, and a further improvement inthe transmission response can be achieved.

(6) Provided with an accelerator position opening amount detection means(accelerator position opening amount sensor) 92 that detects theaccelerator position opening amount, wherein the transmission speedcontrol section (Step S7-Step S11) is configured to make thetransmission speed during the downshift control when it is determinedthat the accelerator position opening amount is at a low opening amountand the an accelerator depression speed is low to be slower than thetransmission speed during a downshift control when only a downshiftrequest of the automatic transmission (belt type continuously variabletransmission) 6 has been generated. Accordingly, in addition to theeffect of any one of (1) to (5), when it can be thought that the driverdoes not want a variation in the driving force, it is possible tosuppress an abrupt variation in the driving force, and to preventimparting discomfort to the driver.

The hybrid vehicle control device of the present invention was describedabove based on the first embodiment, but specific configurations thereofare not limited to this embodiment, and various modifications andadditions to the design can be made without departing from the scope ofthe invention according to each claim in the Claims.

In the first embodiment, an example was shown in which, in thetransmission speed calculation steps illustrated in FIG. 5, thetransmission speed is calculated based on the accelerator positionopening amount/accelerator depression speed/vehicle speed and on the mapA or map B, and the final CL1 pre-engagement transmission speed is setin accordance with the engine stop time. However, the calculation stepsof the CL1 pre-engagement transmission speed are not limited thereto;for example, the steps may be a transmission speed calculation blockduring cooperative control A1 illustrated in FIG. 7.

This transmission speed calculation block during cooperative control A1illustrated in FIG. 7 comprises a map D/map E/map F/map G which are setin advance, a minimum selection operator MIN, and a second switch SW2.

The map D is a transmission speed setting map that uniquely sets thetransmission speed, on the basis of the engine stop time and the vehiclespeed.

The transmission speed setting conditions in this map D are as listedbelow.

-   -   Set to a value faster than the ordinary transmission speed.    -   Set to a slower value as the engine stop time is increased.    -   Set to a slower value as the vehicle speed is increased.    -   Set an upper limit value so as not to delay the engagement of        the first clutch 3.

The map E is a transmission speed setting map that uniquely sets thetransmission speed, on the basis of the accelerator position openingamount and the vehicle speed.

The transmission speed setting conditions in this map E are as listedbelow.

(1) When the accelerator position opening amount is at a medium openingamount or more.

-   -   Set to a value faster than the ordinary transmission speed.    -   Set to a faster value as the accelerator position opening amount        is increased, that is, as the required driving force of the        driver is increased.    -   Set to a slower value as the vehicle speed is increased.    -   Set an upper limit value so as not to delay the engagement of        the first clutch 3.

(2) When the accelerator position opening amount is a low opening amount

-   -   Set to a value slower than the ordinary transmission speed.

The map F is a transmission speed setting map that uniquely sets thetransmission speed, on the basis of the accelerator depression speed andthe vehicle speed.

The transmission speed setting conditions in this map F are as listedbelow.

(1) When the accelerator depression speed is not low

-   -   Set to a value faster than the ordinary transmission speed.    -   Set to a faster value as the accelerator depression speed is        increased, that is, as the required driving force of the driver        is increased.    -   Set to a slower value as the vehicle speed is increased.    -   Set an upper limit value so as not to delay the engagement of        the first clutch 3.

(2) When the accelerator depression speed is low

-   -   Set to a value slower than the ordinary transmission speed.

The minimum selection operator MIN is a selection operator that selectsthe transmission speed that is set to the smallest value from theplurality of inputted transmission speeds and sets the same as the CL1pre-engagement transmission speed.

Furthermore, the map G is a transmission speed setting map that uniquelysets the CL1 post-engagement transmission speed that is applied afterthe first clutch 3 is completely engaged, on the basis of theaccelerator position opening amount and the vehicle speed.

The transmission speed setting conditions in this map G are as listedbelow.

(1) When the accelerator position opening amount is at a medium openingamount or more.

-   -   Set to a value faster than the ordinary transmission speed.    -   Set to a faster value as the accelerator position opening amount        is increased, that is, as the required driving force of the        driver is increased.    -   Set to a slower value as the vehicle speed is increased.    -   An upper limit value is not set, since the first clutch 3 is        engaged.

(2) When the accelerator position opening amount is a low opening amount

-   -   Set to a value slower than the ordinary transmission speed.

Even in the transmission speed calculation steps illustrated in FIG. 7,unless the accelerator position opening amount is at a low openingamount or the depression speed is small, the transmission speed duringcooperative control is set to a value that is faster than the ordinarytransmission speed, and it is possible to prevent a delay in thetransmission response. In addition, it is possible to prevent theengagement of the first clutch 3 taking more time than necessary.

Furthermore, in the first embodiment, an example was shown in which thehybrid vehicle control device of the present invention is applied to anFF hybrid vehicle. However, the control device of the present inventionis not limited to an FF hybrid vehicle, and may be applied to an FRhybrid vehicle, a 4WD hybrid vehicle, and a plug-in hybrid vehicle aswell. In short, the invention may be applied to any hybrid vehicle.

In addition, an example was shown in which the automatic transmission isa belt type continuously variable transmission, but the invention is notlimited thereto, and the automatic transmission may be a steppedautomatic transmission. At this time, a clutch and brake provided insidethe transmission may be used as the second clutch.

The invention claimed is:
 1. A hybrid vehicle control device forcontrolling a drive system including an engine, a motor coupled to theengine via a first clutch, and an automatic transmission, the hybridvehicle control device comprising: a controller programmed to, uponreceiving a mode switch request during the electric vehicle travelingmode, engage the first clutch and shift from an electric vehicletraveling mode where only the motor is a drive source to a hybridvehicle traveling mode where the engine and the motor are drive sources;the controller being further programmed to immediately start a modeswitch control, which shifts from the electric vehicle traveling mode tothe hybrid vehicle traveling mode by engaging the first clutch andstarting the engine, and start a downshift control once a rotationalspeed of the engine has reached a combustion possible rotational speed,upon generation of both the mode switch request and a downshift requestof the automatic transmission, the controller being further programmedto comprise a transmission speed control section which sets atransmission speed during the downshift control to be faster than thetransmission speed during the downshift control when only a downshiftrequest of the automatic transmission is generated.
 2. The hybridvehicle control device according to claim 1, wherein the transmissionspeed control section is programmed to increase the transmission speedduring the downshift control as a required driving force of the driveris increased.
 3. The hybrid vehicle control device according to claim 1,comprising: a timer that detects a stopped time of the engine before themode switch control is started, wherein the transmission speed controlsection is programmed to decrease the transmission speed during thedownshift control when the stopped time of the engine is shorter than apredetermined time as compared to the transmission speed during thedownshift control when the stopped time of the engine is longer than thepredetermined time.
 4. The hybrid vehicle control device according toclaim 1, comprising: a vehicle speed sensor that detects the vehiclespeed, wherein the transmission speed control section is programmed todecrease the transmission speed during the downshift control as thevehicle speed is increased.
 5. The hybrid vehicle control deviceaccording to claim 3, wherein the transmission speed control section isprogrammed to increase the transmission speed during the downshiftcontrol after the first clutch is engaged as compared to thetransmission speed during the downshift control before the first clutchis engaged.
 6. The hybrid vehicle control device according to claim 1,comprising: an accelerator position opening amount sensor that detectsan accelerator position opening amount, the transmission speed controlsection being programmed to decrease the transmission speed during thedownshift control, upon determining that the accelerator positionopening amount is at less than a predetermined opening amount and anaccelerator depression speed is less than a predetermined acceleratordepression speed, as compared to the transmission speed during adownshift control when only the downshift request of the automatictransmission has been generated.
 7. The hybrid vehicle control deviceaccording to claim 2, comprising: a timer that detects a stopped time ofthe engine before the mode switch control is started, wherein thetransmission speed control section is programmed to decrease thetransmission speed during the downshift control when the stopped time ofthe engine is shorter than a predetermined time as compared to thetransmission speed during the downshift control when the stopped time ofthe engine is longer than the predetermined time.
 8. The hybrid vehiclecontrol device according to claim 2, comprising a vehicle speed sensorthat detects the vehicle speed, wherein the transmission speed controlsection is programmed to decrease the transmission speed during thedownshift control as the vehicle speed is increased.
 9. The hybridvehicle control device according to claim 4, wherein the transmissionspeed control section is programmed to increase the transmission speedduring the downshift control after the first clutch is engaged ascompared to the transmission speed during the downshift control beforethe first clutch is engaged.
 10. The hybrid vehicle control deviceaccording to claim 2, comprising an accelerator position opening amountsensor that detects an accelerator position opening amount, thetransmission speed control section being programmed to decrease thetransmission speed during the downshift control, upon determining thatthe accelerator position opening amount is at less than a predeterminedopening amount and an accelerator depression speed is less than apredetermined accelerator depression speed, as compared to thetransmission speed during a downshift control when only the downshiftrequest of the automatic transmission has been generated.
 11. The hybridvehicle control device according to claim 3, comprising a vehicle speedsensor that detects the vehicle speed, wherein the transmission speedcontrol section is programmed to decrease the transmission speed duringthe downshift control as the vehicle speed is increased.
 12. The hybridvehicle control device according to claim 11, wherein the transmissionspeed control section is programmed to increase the transmission speedduring the downshift control after the first clutch is engaged ascompared to the transmission speed during the downshift control beforethe first clutch is engaged.
 13. The hybrid vehicle control deviceaccording to claim 12, comprising an accelerator position opening amountsensor that detects an accelerator position opening amount, thetransmission speed control section being programmed to decrease thetransmission speed during the downshift control, upon determining thatthe accelerator position opening amount is at less than a predeterminedopening amount and an accelerator depression speed is less than apredetermined accelerator depression speed, as compared to thetransmission speed during a downshift control when only the downshiftrequest of the automatic transmission has been generated.
 14. The hybridvehicle control device according to claim 3, comprising an acceleratorposition opening amount sensor that detects an accelerator positionopening amount, the transmission speed control section being programmedto decrease the transmission speed during the downshift control, upondetermining that the accelerator position opening amount is at less thana predetermined opening amount and an accelerator depression speed isless than a predetermined accelerator depression speed, as compared tothe transmission speed during a downshift control when only thedownshift request of the automatic transmission has been generated. 15.The hybrid vehicle control device according to claim 4, comprising anaccelerator position opening amount sensor that detects an acceleratorposition opening amount, the transmission speed control section beingprogrammed to decrease the transmission speed during the downshiftcontrol, upon determining that the accelerator position opening amountis at less than a predetermined opening amount and an acceleratordepression speed is less than a predetermined accelerator depressionspeed, as compared to the transmission speed during a downshift controlwhen only the downshift request of the automatic transmission has beengenerated.
 16. The hybrid vehicle control device according to claim 5,comprising an accelerator position opening amount sensor that detects anaccelerator position opening amount, the transmission speed controlsection being programmed to decrease the transmission speed during thedownshift control, upon determining that the accelerator positionopening amount is at less than a predetermined opening amount and anaccelerator depression speed is less than a predetermined acceleratordepression speed, as compared to the transmission speed during adownshift control when only the downshift request of the automatictransmission has been generated.